<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒子模型</title>

    <style>
        #div1{
            width:200px;
            height:200px;
            box-sizing: border-box;
            background-color: blue;
            padding: 20px;
            border: 5px solid red;
            margin: 30px;
        }
    </style>
</head>
<body>
    <div id="div1">
        我是我是我是我是我是我是我是我是我是我是我是我是
    </div>
    <span>
        我是1我是2我是3
    </span>
    <span>我是4我是5我是6</span>
</body>
</html>